1. Technical Field
The present invention relates to a cassette for radiographic imaging.
2. Related Art
An X-ray imaging has been widely used in the fields of medical diagnosis or nondestructive inspection. In a general X-ray imaging, X-rays are irradiated to a subject and attenuated at each part of the subject. Then, X-rays transmitted through the subject are detected to obtain X-ray images based on the intensity distributions of X-rays.
As an X-ray image recording medium, there have been used, for example, a combination of an intensifying screen which generates fluorescence when exposed to X-rays and a film photosensitive to the fluorescence, or a photostimulable phosphor (accumulative phosphor) panel which accumulates the intensity distributions of X-rays as latent images when exposed to X-rays, and emits fluorescence in accordance with the latent images by subsequent irradiation of excitation light such as laser.
Recently, a flat panel detector (FPD) has also been used as an X-ray image recording medium, which generates digital image data by using a semiconductor device that detects an X-ray and converts the detected X-ray into an electric signal.
Further, a so-called cassette configured to accommodate the X-ray image recording medium in a portable case has been widely used in an X-ray imaging.
Such cassettes are frequently exposed to load or impact due to the form of usage. Further, since the radiological conversion panel, electronic parts and circuit board, which are precision electronic instruments, are accommodated in the cassette, the structure of the case should be configured such that an external load has no effect on the radiological conversion panel, electronic parts and circuit board. Further, in addition to having rigidity (impact resistance) against external load, the case is also required to be light weight and thin.
In order to protect the X-ray image recording medium from load or impact, a buffer material is provided, for example, in a gap between the case and X-ray image recording medium.
Moreover, a case that accommodates X-ray image recording medium is constituted with, for example, a top plate part and a bottom plate part which have a substantially rectangular shape, and a frame member which is attached thereto. The cassette described in JP-A-2010-039267 and JP-A-2009-300757 employs a case structure that enhances robustness.
In the cassette described in JP-A-2010-039267, the case is constituted with a front member including a top plate part which has a substantially rectangular shape and a frame part which is vertically formed on four side edges of the top plate part, and a back member which closes a bottom part opening of the front member. Further, it has been suggested that a top plate part and a frame part that constitute a front member are integrally formed by a resin material, and as a result, the strength of a front member is enhanced, thereby preventing deformation while suppressing the load increase.
In the cassette disclosed in JP-A-2010-039267, a top plate part and a frame part of a front member are integrally formed. With this arrangement, while the overall bending rigidity and torsional rigidity of the front member are increased, the warpage of the top plate part on which the load of the subject is imposed is not suppressed sufficiently. Further, by the warpage of the top plate part, the load or impact may be imposed on X-ray image recording medium disposed to oppose the top plate part.
In consideration of the above circumstances, an object of the present invention is to provide a cassette for radiographic imaging having an excellent load carrying capacity and impact resistance.